The semi-conductor industry undertakes the precision manufacture of small parts, and the machinery required to make those parts uses purified pressurized liquids which pass through long lengths of tubing. The tubing used in such machines is very expensive because it has electropolished inner surfaces to prevent contamination of the purified liquids flowing therein. The lengths of tubing are formed by welding sections of tubing end to end. Such tubing typically has a diameter ranging from 1/8 inch to 1 inch or more and the welds that join the lengths must be perfectly formed such that the tube, including the welds, will not contaminate the liquid passing therethrough. Also, the welding process consumes materials which could contaminate the liquid passing through the tube, and if the weld is not perfectly formed, traces of unconsumed welding material may remain on the inner surface of the tube.
To test the quality of a weld, a welding machine is first used to weld the ends of two short pieces of tubing together, after which a length of the sample, including the weld, is cut lengthwise, and the sample is rolled opened and laid flat so that the inner surface thereof can be inspected. The quality of a weld can be determined by visually inspecting the color and texture of the weld surface.
To maintain the required quality of the weld made by a welding machine a sample weld is inspected by independent inspectors at regular intervals. Some specifications require that samples be inspected at the beginning and at the end of each day while other specifications require that an inspection be made as frequently as every tenth weld. The inspectors mark each sample they inspect and retain the samples as evidence that the inspections were properly conducted.
Prior to the present invention, to prepare a weld sample for inspection, a length of tubing including a sample weld was manually moved against a rotating blade to first make a longitudinal cut in the length of the sample, after which a second transverse cut was also manually made. Ideally, the second cut would not be made through the entire cross section of the tubing, leaving a small section of the tubing wall to retain the cross-cut sample to the remaining tubing length. After the sample has been cut, pliers or other tools were used to spread the sample flat so that it could be visually inspected.